The macronutrient______is a component of all organic compounds but is not obtained from soil.

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks for a macronutrient that is a component of all organic compounds but is not obtained from the soil.

2. **Identifying Organic Compounds**: Organic compounds are primarily made up of carbon, hydrogen, and oxygen. Therefore, we need to identify which of these macronutrients fits the criteria of being a component of all organic compounds.

3. **Analyzing Macronutrients**: The major macronutrients include carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Among these, carbon is unique because it is the backbone of all organic compounds.

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